From the standpoint of the moral theologian, perhaps the most influential aspect of Karl Rahner’s theology is the thesis of the fundamental option, that is, the claim that the individual’s status before God is determined by a basic, freely chosen and prethematic orientation of openness towards, or rejection of God which takes place at the level of core or transcendental freedom. This paper argues that this notion of the fundamental option is problematic because it is not concrete enough to provide an adequate interpretation of our actual experience. Yet this problem cannot be addressed through reviving the traditional account of mortal and venial sins, which are equally problematic, albeit in a somewhat different way. The second half of the paper explores the alternative offered by Aquinas’s account of charity, which, it is argued, does provide us with an account of grace sufficiently rich and concrete to illuminate human experience. However, this alternative is likewise problematic, most notably in its commitment to the view that charity is lost through one mortal sin. Yet Aquinas’s account of charity provides resources for an internal critique and revision on this point, as can be seen through a consideration of cases of “sinful saints.”